Microcatheter with distal tip portion and proximal solution lumen

ABSTRACT

There is provided a microcatheter having a proximal solution lumen and a distal tip portion with a guidewire lumen. The microcatheter and methods of use thereof allows for introduction of solution into a vessel while manipulating the guidewire and/or the microcatheter itself. The solution may be a contrast solution, for viewing of the vessel, a therapeutic or diagnostic solution, or any other type of solution.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application of U.S.patent application Ser. No. 13/079,866, filed on Apr. 5, 2011 which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention is directed to a microcatheter having a tipportion for holding a guidewire therein, and a proximal body having asolution lumen.

More specifically, the present invention is directed to a microcatheterwhich is designed to hold solution such as a contrast solution or atherapeutic or diagnostic solution in a proximal lumen, andsimultaneously hold a guidewire in a distal tip lumen, and which can beused to inject solution into a vessel while manipulating the guidewireor the microcatheter in the vessel.

BACKGROUND

Microcatheters are commonly used by physicians to access discreetregions of the arterial vasculature during interventional procedures.They are typically used to facilitate the placement and exchange ofguidewires, and may also be used to subselectively infuse or delivertherapeutic agents. Some examples of microcatheters are Skyway® andMinnie® (Vascular Solutions, Inc.), Rebar®, Nautica™ and Echelon™ (ev3,Inc.), Quick-Cross® Select (Spectranetics, Inc.), Tracker® Excel™(Boston Scientific, Inc.) and Corsair® (Asahi Intecc) all of which aresingle lumen catheters, with the lumen sized to have a substantiallyclose fit with a guidewire placed therethrough in order to providesupport to the guidewire: for example, to prevent the guidewire frombuckling under pressure when encountering a lesion. These devices may becomprised of a single or multiple-layer polymer shaft, or a polymershaft with a stainless-steel braid. To perform perfusion of diagnosticor therapeutic agents, the guidewire must be removed from the lumen, andthis may result in a loss of access to the distal vasculature.

SUMMARY OF THE INVENTION

There is provided, in accordance with embodiments of the presentinvention, a microcatheter. The microcatheter includes an elongatetubular body having a body proximal end, a body distal end and asolution lumen extending axially through the elongate tubular body. Theelongate tubular body has an outlet port at the body distal end. Themicrocatheter further includes a tip portion positioned distal to thebody distal end, having a tip portion proximal end, a tip portion distalend, and a tip portion lumen extending axially through the tip portion.The tip portion lumen is sized for a substantially close fit for aguidewire to be held therein and has a diameter which is smaller than adiameter of the elongate tubular body. The microcatheter furtherincludes a spine wire extending through the elongate tubular body andthrough the tip portion, and having a spine wire proximal portion and aspine wire distal portion, wherein at least a portion of the spine wiredistal portion is positioned within the tip portion, wherein the spinewire distal portion is more malleable than the spine wire proximalportion such that at least the tip portion distal end may be shaped to adesired configuration.

In accordance with further features in embodiments of the invention, theelongate tubular body is continuous with the tip portion and configuredto hold a proximal portion of the guidewire therein. In otherembodiments, the tip portion is separate from the tubular body, and maybe eccentric thereto. In some embodiments, the tip portion has aproximal opening at the tip portion proximal end, and the proximalopening is not co-linear with the outlet port. The tip portion may be atleast partially radiopaque, and may have a length of 10 mm-120 mm. Aninner diameter of the tip portion may be approximately 0.002″ largerthan a diameter of a guidewire to be placed therethrough, or may be anysize such that a tight fit is provided around the guidewire. In someembodiments, a balloon may be positioned on the distal tip portion,wherein the balloon may be made of a compliant material, or asemi-compliant material, depending on the application. The balloon maybe positioned on a proximal end of the tip portion, on a distal end ofthe tip portion, or anywhere in between depending on the application.

There is provided, in accordance with another embodiment of the presentinvention, a microcatheter. The microcatheter includes an elongatetubular body having a body proximal end, a body distal end, and asolution lumen extending axially through said elongate tubular body, theelongate tubular body having an outlet port at the body distal end, anda tip portion having a tip portion proximal end, a tip portion distalend, and a tip portion lumen extending axially through the tip portion,the tip portion lumen sized for a substantially close fit for aguidewire to be held therein, wherein the tip portion has a proximalopening at the tip portion proximal end and wherein the tip portion iseccentric to the elongate tubular body and wherein the proximal openingof the tip portion is not co-linear with the outlet port.

In accordance with further features in embodiments of the presentinvention, the elongate tubular body and the tip portion may havesubstantially the same diameter or may have different diameters. The tipportion proximal end is positioned distal to the outlet port of theelongate tubular body. The tip portion may be at least partiallyradiopaque, and in some embodiments, the tip portion is comprised of apolymer compounded with radiopaque material. The tip portion may be in arange of 10 mm to 120 mm long. An inner diameter of the tip portion maybe approximately 0.002″ larger than a diameter of a guidewire to beplaced therethrough.

There is provided, in accordance with another embodiment of the presentinvention, a method for providing a solution to a portion of a vessel.The method includes providing a microcatheter having an elongate tubularbody with a lumen extending axially therethrough and an outlet port, anda tip portion distal to the elongate tubular body, the tip portionhaving a tip portion lumen extending axially therethrough. The methodincludes placing a guidewire in the vessel, advancing the microcatheterinto the vessel by placing the guidewire through at least the tipportion of the microcatheter and advancing the microcatheter over theguidewire, introducing solution into the elongate tubular body at thebody proximal end, and injecting the solution into the vessel throughthe outlet port.

According to further features in embodiments of the present invention,the solution may be a contrast solution, a therapeutic solution, adiagnostic solution, or any other solution which may be introduced intoa vessel. The method may include alternately injecting the solution andadvancing the guidewire in the vessel. In some embodiments, theinjecting may be done in short puffs. In some embodiments, the guidewireis placed through both the elongate tubular body and the tip portion,and the solution is injected into the elongate tubular body with theguidewire therein. In other embodiments, the tip portion is separatefrom the elongate tubular body, and the guidewire is placed only throughthe tip portion. In some embodiments, the guidewire may be exchanged byusing the tip portion as a rapid exchange distal rail.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the embodiments of the present invention,suitable methods and materials are described below. In case of conflict,the patent specification, including definitions, will control. Inaddition, the materials, methods, and examples are illustrative only andnot intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of variousembodiments of the present invention only, and are presented in thecause of providing what is believed to be the most useful and readilyunderstood description of the principles and conceptual aspects of theinvention. In this regard, no attempt is made to show structural detailsof the invention in more detail than is necessary for a fundamentalunderstanding of the invention, the description taken with the drawingsmaking apparent to those skilled in the art how the several embodimentsof the invention may be embodied in practice.

In the drawings:

FIG. 1 is a schematic illustration of a microcatheter in accordance withembodiments of the present invention;

FIG. 2 is a cross-sectional illustration of a distal portion of themicrocatheter of FIG. 1, in accordance with embodiments of the presentinvention;

FIG. 3 is a schematic illustration of a distal portion of themicrocatheter of FIG. 1, with a guidewire 32 in place and with solutionbeing pushed through an outlet port in accordance with embodiments ofthe present invention;

FIGS. 4A and 4B are schematic illustrations of a distal portion of themicrocatheter having a balloon, in accordance with another embodiment ofthe present invention;

FIGS. 5A and 5B are cross-sectional illustrations of a microcatheter inaccordance with an additional embodiment of the present invention;

FIGS. 6A and 6B are schematic illustrations of a microcatheter inaccordance with yet another embodiment of the present invention;

FIGS. 7A-7E are schematic illustrations of steps of a method ofproviding a solution to a portion of a vessel, in accordance withembodiments of the present invention;

FIG. 8 is a schematic illustration of an additional method step inaccordance with embodiments of the present invention;

FIGS. 9A-9F are schematic illustrations of steps of a method of crossinga lesion in a vessel, in accordance with additional embodiments of thepresent invention; and

FIG. 10 is a cross-sectional illustration of a distal portion of themicrocatheter of FIG. 1, in accordance with additional embodiments ofthe present invention.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the drawings have not necessarily been drawnaccurately or to scale. For example, the dimensions of some of theelements may be exaggerated relative to other elements for clarity orseveral physical components may be included in one functional block orelement. Further, where considered appropriate, reference numerals maybe repeated among the drawings to indicate corresponding or analogouselements. Moreover, some of the blocks depicted in the drawings may becombined into a single function.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. It will be understood by those of ordinary skill in the artthat embodiments of the present invention may be practiced without thesespecific details. In other instances, well-known methods, procedures,components and structures may not have been described in detail so asnot to obscure the present invention.

The present invention relates to a microcatheter having a proximalsolution lumen and methods of use thereof. The microcatheter of thepresent invention allows for injection of solution into a vessel with aguidewire in the vessel at the same time. When the solution is acontrast solution, the design of the present invention allows forenhanced viewing as the wire is advanced, and also provides minimizationof contrast solution used. Further advantages of the design of themicrocatheter of the present invention will be described hereinbelow.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein are for the purpose ofdescription and should not be regarded as limiting.

Reference is now made to FIG. 1, which is a schematic illustration of amicrocatheter 10 in accordance with embodiments of the presentinvention. Microcatheter 10 has an elongate tubular body 12 having abody proximal end 14 and a body distal end 16. Body proximal end 14 isconnected to an introduction port 13 which can be used for introductionof a solution, such as contrast solution, and for introduction of aguidewire into microcatheter 10. Introduction port 13 may include aguidewire port 15 for introduction of a guidewire 32 therethrough and asolution port 17 for introduction of solution. A tip portion 22 ispositioned distal to body distal end 16. Tip portion 22 may becontinuous with elongate tubular body 12 or may be separated therefrom,as will be described in further detail thereinbelow. An outlet port 20is positioned at body distal end 16, proximal to tip portion 22. Outletport 20 may comprise one or multiple openings. Tip portion 22 has a tipportion proximal end 24, and a tip portion distal end 26. Tip portion 22has a length of between 10 mm and 120 mm. Tip portion 22 is sized tosnugly fit a guidewire therethrough along the entire length of tipportion 22. Thus, tip portion 22 may have an inner diameter on an orderof approximately 0.002″ bigger than a diameter of a guidewire to beplaced therethrough so as to obtain a tight fit. For example, tipportion 22 may have an inner diameter of 0.016″ for positioning of a0.014″ diameter guidewire therethrough, or tip portion 22 may have aninner diameter of 0.020″ for positioning of a 0.018″ guidewiretherethrough, or tip portion 22 may have an inner diameter of 0.037″ forpositioning of a 0.035″ guidewire therethrough. It should be readilyapparent that tip portion 22 may have other diameters, provided that aguidewire fits snugly inside. The tight fit for the guidewire providesfor minimization of the distal portion of microcatheter 10 and enhancedpushability and maneuverability of the guidewire. In addition, in someembodiments, the tight fit also acts as a seal so that a solutionintroduced through elongate tubular body 20 will exit through outletport 20 and not through tip portion 22. A guidewire 32 is shownpositioned within microcatheter 10 and extending through tip portion 22.

Elongate tubular body 12 may have various embodiments, as will bedescribed with reference to FIGS. 2-5 hereinbelow. In all of theembodiments, elongate tubular body 12 includes a solution lumen, forintroducing contrast solution, or medications or other types ofsolutions into the vessel. In some embodiments, the same lumen is usedfor guidewire 32, while in other embodiments, a separate lumen is usedfor guidewire 32. In some embodiments, guidewire 32 is positionedthrough tip portion 22 only, and not through elongate tubular body 12.In all of the embodiments, guidewire 32 is positionable through at leasttip portion 22.

Reference is now made to FIG. 2, which is a cross-sectional illustrationof a distal portion of mircrocatheter 10, in accordance with embodimentsof the present invention. In the embodiment shown in FIG. 2, elongatetubular body 12 comprises a solution lumen 18 having a diameter which issufficiently wide to accommodate both guidewire 32 and a solution to beintroduced into the vessel. Solution lumen 18 has a solution lumenproximal end (not shown) which is in fluid communication withintroduction port 13, and a solution lumen distal end 19 having outletport 20 at a distal end thereof. Outlet port 20 may comprise one ormultiple openings. Tip portion 22 has a tip portion lumen 28 extendingfrom tip portion proximal end 24 to tip portion distal end 26. Guidewire32 (not shown) may be positioned through solution lumen 18 and furtherthrough tip portion lumen 28 and out through tip portion distal end 26.Guidewire 32 positioned through tip portion 22 essentially seals tipportion 22, such that a solution introduced through solution lumen 18while a guidewire is in place exits via outlet port 20 at body distalend 16. Thus, it is possible to introduce a solution, such as contrastsolution, for example, into the vessel while simultaneously manipulatingguidewire 32 and microcatheter 10 within the vessel.

An additional feature of microcatheter 10 includes a spine wire 30embedded within a wall of microcatheter 10. Spine wire 30 is preferablya spring tempered metal wire, such as 304 stainless steel or nitinol,having a stiffer proximal end (0.015″ outer diameter) and a moreflexible distal end, tapering to a dimension of 0.003″. Thus, spine wire30 is both a stiff and a flexible wire which runs along tip portion 22and elongate tubular body 12 of microcatheter 10. Elongate tubular body12 may be comprised of a polymeric material, such as nylon, and thus hasflexibility for advancement through the vessel, but may not havesufficient stiffness for pushability and torqueability. Thus, spine wire30 provides stiffness to elongate tubular body 12 to enhance pushabilityand torqueability of microcatheter 10. Moreover, spine wire 30 has atapered distal end to provide increased flexibility while maintainingand transmitting the push and torque properties of elongate tubular body12 to a distal tip of microcatheter 10.

Reference is now made to FIG. 10, which is an illustration ofmicrocatheter 10 in accordance with another embodiment of the presentinvention. In the embodiment shown in FIG. 10, spine wire 30 has a spinewire proximal end 31 and a spine wire distal end 34. Spine wire distalend 34 includes a malleable portion 50, which extends from a distal mosttip of spine wire 30 and proximally for a distance of between 1 and 120mm. In some embodiments, distal end 34 also includes a stiff portion 52which is proximal to malleable portion 50. The term “stiff portion” isdefined herein to be stiff relative to malleable portion 50. Stiffportion 52 may also be bendable, but not as bendable or malleable asmalleable portion 50. Malleable portion 50 of spine wire distal end 34is flattened, heat-treated or otherwise made more malleable than spinewire proximal end 31 and in some cases than stiff portion 52 of spinewire distal end 34, such that at least some of tip portion distal end 26may be shaped, straightened and/or reshaped to a desired configuration.Spine wire 30 is embedded in the material of microcatheter 10 eitheralong an entire length of microcatheter 10 or along a portion thereof,but in any case at least within tip portion 22. The material ofmicrocatheter 10 and/or tip portion 22 is, for example, a polymer. Thecombination of metal spine wire 30 plus the microcatheter material(i.e., polymer), provides for bending of the combined spine wire/tipportion manually, and allows for the new position to be maintained dueto the hardness of the polymer material. Thus, a user can manually bendthe combined spine wire/tip portion to form a bent portion 53 having apre-determined angle as shown in FIG. 10. This allows for reuse of thesame microcatheter for different vessel anatomies and customization ofthe angle of bend for each insertion of the microcatheter into thevessel. The angled tip portion allows for customized steering of theguidewire within the vessel.

Microcatheter 10 may further comprise at least one radiopaque marker 38included in tip portion 22. Radiopaque marker 38 is comprised of anyradiopaque material, such as tungsten, platinum/iridium or gold, forexample, and is embedded within tip portion 22 so that a position of tipportion 22 in the vessel can be viewed. In another embodiment, tipportion 22 is itself comprised of radiopaque material. This can be done,for example, by compounding a polymer with radiopaque material.

Reference is now made to FIG. 3, which is a schematic illustration of adistal portion of microcatheter 10 with guidewire 32 in place throughsolution lumen 18 and through tip portion 22, and with solution beingpushed through outlet port 20. Elongate tubular body 12 is shown withspine wire 30 (shown in thin dotted lines) embedded therein. Solutionlumen 18 holds both solution and guidewire 32. Guidewire 32 is showninside solution lumen 18 (with thick dotted lines), inside tip portion22 (with thick dotted lines) and extending distally outside of tipportion 22. Solution is depicted via arrows 40 exiting via outlet port20. As depicted in FIG. 3, tip portion 22 is sized to provide support toguidewire 32 positioned therein by providing a close fit for guidewire32 along an entire length of tip portion 22. A distal portion 35 ofguidewire 32 is shown just distally past tip portion 22.

Reference is now made to FIGS. 4A and 4B, which are schematicillustrations of a distal portion of microcatheter 10 in accordance withanother embodiment of the present invention. In this embodiment, aballoon 36 is positioned on tip portion 22. Balloon 36 may be atproximal end 24 of tip portion 22, as shown in FIG. 4A, or at distal end26 of tip portion 22, as shown in FIG. 4B, or at any point in between,depending on the application. An additional inflation lumen may be addedfor introduction of inflation fluid into balloon 36 for expansion ofballoon 36. In this case, an inflation port would be added tointroduction port 13 at proximal end 14 of microcatheter 10. Balloon 36may be a compliant or semi-compliant balloon, both types of which arecommonly known in the art. The embodiment shown in FIG. 4A, when usedwith a semi-compliant balloon in particular, is suitable, for example,for treating a chronic total occlusion (CTO). In a case of CTO, balloon36 can be used to break up the lesion and then advance guidewire 32through the lesion, while simultaneously injecting contrast solutionthrough outlet port 20 to view advancement of guidewire 32. Theembodiment shown in FIG. 4B, when used with a compliant balloon, may besuitable for retrograde pedal artery access. Generally, in suchprocedures, a hollow needle is placed in the foot, advanced to thefemoral artery, and a guidewire is advanced through the hollow needle. Asheath is introduced from above the blockage through the femoral artery.The guidewire is further advanced through the hollow needle to be placedthrough the sheath and to then be pushed through the lesion. However, itis difficult to thread the guidewire into the sheath, particularlybecause the sheath is generally relatively short. The microcatheter ofthe present invention can be used instead of a sheath, and may beadvanced to the blockage area. The compliant balloon 36 can then bepulled back and used as a funnel to catch the guidewire coming from thehollow needle, as will be described in greater detail hereinbelow.

Reference is now made to FIGS. 5A and 5B, which are cross-sectionalillustrations of microcatheter 10 in accordance with an additionalembodiment of the present invention. Microcatheter 10 has an elongatetubular body 12 having a body proximal end 14 and a body distal end 16.Body proximal end 14 is connected to an introduction port 13 which canbe used for introduction of a solution through solution port 17, such ascontrast solution, and for introduction of a guidewire through guidewireport 15, into microcatheter 10. A tip portion 22 is positioned distal tobody distal end 16. Tip portion 22 is continuous with elongate tubularbody 12. An outlet port 20 is positioned at body distal end 16, proximalto tip portion 22. Outlet port 20 may comprise one or multiple openings.Tip portion 22 has a tip portion proximal end 24, and a tip portiondistal end 26. Tip portion 22 has a length of between 10 mm and 120 mm.Tip portion 22 is sized to snugly fit a guidewire therethrough and mayfurther include a radiopaque marker 38.

In the embodiment shown in FIGS. 5A and 5B, elongate tubular body 12comprises a solution lumen 18 and a separate guidewire lumen 21, whereinguidewire lumen 21 leads directly into tip portion lumen 28 so that aguidewire 32 may be positioned through elongate tubular body 12 anddirectly into tip portion 22. A view of microcatheter 10 in accordancewith this embodiment is shown in FIG. 5B with guidewire 32 positionedtherein. Solution lumen 18 extends from elongate tubular body proximalend 14 to elongate tubular body distal end 16 and ends distally inoutlet port 20. Thus, a solution is introduced through solution lumen 18which runs alongside but is separated from guidewire lumen 21. Spinewire 30 is embedded within elongate tubular body 12 and may extenddistally through tip portion 22. Thus, it is possible to introduce asolution, such as contrast solution, for example, into the vessel whilesimultaneously manipulating guidewire 32 and microcatheter 10 within thevessel.

Reference is now made to FIGS. 6A and 6B, which are schematicillustrations of a microcatheter 10 in accordance with yet anotherembodiment of the present invention. Microcatheter 10 has an elongatetubular body 12 having a body proximal end 14 and a body distal end 16.Body proximal end 14 is connected to an introduction port 13 which canbe used for introduction of a solution, such as contrast solution.Elongate tubular body 12 comprises a solution lumen 18. A separate tipportion 22 is connected to distal end 16 of elongate tubular body 12,and has a separate tip portion lumen 28. Tip portion 22 is separatedfrom and eccentric to elongate tubular body 12. Tip portion 22 may bedescribed as a distal rail, attached to body distal end 16. An outletport 20 is positioned at body distal end 16, wherein outlet port 20 isan opening from solution lumen 18 into the vessel. Tip portion 22 has atip portion proximal end 24, and a tip portion distal end 26 and aradiopaque marker 38. Tip portion 22 has a length of between 10 mm and30 mm or any length suitable for rapid exchange of wires. Tip portion 22is sized to snugly fit a guidewire therethrough.

Guidewire 32 is positioned only in tip portion lumen 28, and not insolution lumen 18. Solution lumen 18 is reserved for introduction ofsolution therethrough. In this embodiment, tip portion 22 has a proximalopening 25 at tip portion proximal end 24 and a distal opening 27 at tipportion distal end 26. Proximal opening 25 is not co-linear with outletport 20. Guidewire 32 is introduced directly into tip portion lumen 28,and not through introduction port 13. In this embodiment, introductionport 13 may not include guidewire port 17. Spine wire 30 is embeddedwithin elongate tubular body 12 and may extend distally to tip portion22. Thus, it is possible to introduce a solution, such as contrastsolution, for example, into the vessel while simultaneously manipulatingguidewire 32 and microcatheter 10 within the vessel.

In one embodiment, as shown in FIG. 6A, tip portion 22 and elongatetubular body 12 have different diameters. Thus, if desired, differentsized wires may be introduced through each of tip portion lumen 28 andsolution lumen 18. In another embodiment, as shown in FIG. 6B, tipportion 22 and elongate tubular body 12 have substantially the samediameter. In this embodiment, wires having the same size may beintroduced through each of tip portion lumen 28 and solution lumen 18.

Reference is now made to FIGS. 7A-7E, which are schematic illustrationsof a method of using microcatheter 10 in accordance with embodiments ofthe present invention. First, as shown in FIG. 7A, guidewire 32 isintroduced into a vessel 202. In some embodiments, an occlusion 204 maybe present in vessel 202, and microcatheter 10 is used to treatocclusion 204. Next, as shown in FIG. 7B, microcatheter 10 is introducedover guidewire 32 into vessel 202. Although the embodiment shown inFIGS. 7A-7E depict microcatheter 10 in accordance with the embodimentsshown in FIGS. 1-5 and FIG. 10 of the present application, it should bereadily apparent that microcatheter 10 in accordance with the embodimentshown in FIG. 6, or any other embodiments of microcatheter 10 which areincluded within the scope of the present invention, may be used for themethod shown in FIGS. 7A-7E.

Once microcatheter 10 is advanced, a solution, shown by arrows 40, maybe introduced into vessel 202, as shown in FIG. 7C. The solution may be,for example, a contrast solution for internal viewing of vessel 202.Alternatively, the solution may be a diagnostic or therapeutic solutionfor treatment of occlusion 204. A particular advantage of the design ofmicrocatheter 10 is that the solution may be stored within solutionlumen 18 of microcatheter 18, and introduced into vessel 202 only whenneeded, and in variable amounts. For example, contrast solution may bestored in solution lumen 18, and introduced into vessel 202 in shortpuffs so as to minimize exposure to the potentially harmful solution. Inthis way, microcatheter 10 and guidewire 32 may be advanced and viewed,either alternatingly or simultaneously or in any other sequence, so asto maximize viewing and minimize exposure to contrast solution. Thus, ina first configuration the distal end of the movable guidewire is in afirst position with respect to the tip portion and in a secondconfiguration the distal end of the movable guidewire is in a secondposition with respect to the tip portion, wherein the second position isdistal to the first position, such that the guidewire may be advancedwithin the vessel past the tip portion while also being supported by thetip portion. Similarly, when the solution is a therapeutic or diagnosticsolution, the amount introduced into vessel 202 may be varied in realtime, depending on factors taken into account at the time of theprocedure. Such factors may include, for example, the composition orsize of occlusion 204, or other factors. Advancement of microcatheter 10is shown in FIG. 7D. Another advantage of the present invention is thatguidewire 32 can occlude tip portion 22 due to its tight fit, thusenabling the solution to enter the vessel only via outlet port 20. Asshown in FIG. 7E, in some embodiments wherein tip portion 22 has a bentportion 53, microcatheter 10 can be positioned through a side branchvessel due to the angling of tip portion 22.

Reference is now made to FIG. 8, which is a schematic illustration ofmicrocatheter 10 with a balloon 36 on tip portion 22. Tip portion 22 maybe advanced into an area of vessel 202 having occlusion 204, and balloon36 may be expanded to break up occlusion 204. The remaining steps ofintroducing solution and manipulating the guidewire may be done in thisembodiment as well.

Reference is now made to FIGS. 9A-9F, which are schematic illustrationsof a method of using microcatheter 10 for retrograde access of an arterysuch as a pedal artery, for example. It should be readily apparent thatany catheter having a compliant balloon on its distal end may be used inthe present method, and not just a microcatheter as described. As shownin FIG. 9A, first a retrograde guidewire 33 is advanced into a vessel302 having an occlusion 304. Retrograde guidewire 33 is introduced intovessel 302 from a retrograde direction, via a hollow needle 400, forexample. Next, a guidewire 32 is advanced into vessel 302 from anantegrade direction, as shown in FIG. 9B. Next, microcatheter 10, or anyother suitable catheter, having balloon 36 on tip portion 22 is advancedover guidewire 32. Balloon 36 is a compliant balloon, and is positionedat a distal portion of tip portion 22. As described above with referenceto FIGS. 7A-7D, solution may be introduced through outlet port 20 duringany point in the advancement of microcatheter 10 into vessel 302. Whenmicrocatheter 10 is in place on the antegrade side of occlusion 304,guidewire 32 is removed from microcatheter 10, and balloon 36 isexpanded, as shown in FIG. 9D. Next, as shown in FIG. 9E, microcatheter10 is pulled back proximally, shown by arrows 42, and due to thecompliant property of balloon 36, balloon 36 forms a funnel shape withinthe vessel 302 and/or within the occlusion 304. Next, as shown in FIG.9F, retrograde guidewire 33 may be advanced through occlusion 304 andinto tip portion 22 of microcatheter 10. Because of the funnel-shape ofballoon 36, it is relatively easy to find the opening in tip portion 22.Retrograde guidewire 33 may be comprised of a flexible material and/ordesign (e.g. coil springs) so as not to puncture balloon 36. It shouldbe readily apparent that guidewire 32 may alternatively be removed frommicrocatheter 10 just before advancement of retrograde guidewire 33.Once retrograde guidewire 33 is in microcatheter 10, retrogradeguidewire 33 may be advanced proximally through microcatheter 10, andthen used to replace guidewire 32 for the procedure to follow.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

What is claimed is:
 1. A microcatheter comprising: an elongate tubularbody having a body proximal end, a body distal end and a solution lumenextending axially through said elongate tubular body, said elongatetubular body comprising an outlet port at said body distal end; a tipportion positioned distal to said body distal end, said tip portionhaving a tip portion proximal end, a tip portion distal end and a tipportion lumen extending axially through said tip portion, said tipportion lumen sized for a substantially close fit for a guidewire to beheld therein, wherein said tip portion has a smaller diameter than saidelongate tubular body; and a spine wire extending through said elongatetubular body and through said tip portion, said spine wire having aspine wire proximal portion and a spine wire distal portion, wherein atleast a portion of said spine wire distal portion is positioned withinsaid tip portion, wherein at least a portion of said spine wire distalportion is more malleable than said spine wire proximal portion suchthat at least said tip portion distal end may be pre-shaped to a desiredconfiguration.
 2. The microcatheter of claim 1, wherein said tip portionproximal end is positioned distal to said outlet port of said elongatetubular body.
 3. The microcatheter of claim 1, wherein said elongatetubular body is continuous with said tip portion, and is configured tohold a proximal portion of the guidewire therein.
 4. The microcatheterof claim 1, wherein a diameter of said solution lumen is larger than adiameter of said tip portion lumen.
 5. The microcatheter of claim 1,wherein said tip portion is comprised of a polymer and wherein saidspine wire is embedded within the polymer.
 6. The microcatheter of claim1, wherein said tip portion is in a range of 10 mm to 120 mm long. 7.The microcatheter of claim 1, wherein an inner diameter of said tipportion is approximately 0.002″ larger than a diameter of a guidewire tobe placed therethrough.
 8. The microcatheter of claim 1, wherein saidoutlet port comprises an opening at said body distal end, wherein saidopening leads directly into the vessel.
 9. The microcatheter of claim 1,further comprising a balloon positioned on said distal tip portion. 10.The microcatheter of claim 14, wherein said balloon is comprised of atleast one of: a compliant material, a semi-compliant material or anon-compliant material.
 11. The microcatheter of claim 1, furthercomprising a movable guidewire positioned within said tip portion, themovable guidewire having a distal end, wherein entirely along saidlength of said tip portion, said tip portion lumen is sized for asubstantially close fit for the movable guidewire to be held thereinthus providing support and enhanced pushability to the movableguidewire, wherein in a first configuration the distal end of themovable guidewire is in a first position with respect to the tip portionand in a second configuration the distal end of the movable guidewire isin a second position with respect to the tip portion, wherein the secondposition is distal to the first position, such that the guidewire may beadvanced and manipulated within the vessel past the tip portion whilealso being supported by the tip portion, and such that when said movableguidewire is positioned within said tip portion, solution from saidsolution lumen is configured to exit through said outlet port and intothe vessel.
 12. A microcatheter comprising: an elongate tubular bodyhaving a body proximal end, a body distal end, and a solution lumenextending axially through said elongate tubular body, said elongatetubular body comprising an outlet port at said body distal end; and atip portion having a tip portion proximal end, a tip portion distal end,and a tip portion lumen extending axially through said tip portion, saidtip portion lumen sized for a substantially close fit for a guidewire tobe held therein, wherein said tip portion has a proximal opening at saidtip portion proximal end and wherein said tip portion is eccentric tosaid elongate tubular body and wherein said proximal opening of said tipportion is not co-linear with said outlet port.
 13. The microcatheter ofclaim 12, wherein said elongate tubular body and said tip portion havesubstantially the same diameter.
 14. The microcatheter of claim 12,wherein said tip portion proximal end is positioned distal to saidoutlet port of said elongate tubular body.
 15. The microcatheter ofclaim 12, further comprising a spine wire extending along a length ofsaid elongate tubular body and bonded thereto, said spine wire furtherat least partially connected to said tip portion.
 16. The microcatheterof claim 15, said spine wire having a spine wire proximal portion and aspine wire distal portion, wherein at least a portion of said spine wiredistal portion is positioned within said tip portion, wherein said spinewire distal portion is more malleable than said spine wire proximalportion such that at least said tip portion distal end may be shaped toa desired configuration.
 17. The microcatheter of claim 15, wherein saidtip portion is comprised of a polymer and wherein said spine wire isembedded within the polymer.
 18. The microcatheter of claim 12, whereinsaid tip portion is in a range of 10 mm to 120 mm long.
 19. Themicrocatheter of claim 12, wherein an inner diameter of said tip portionis approximately 0.002″ larger than a diameter of a guidewire to beplaced therethrough.
 20. A method for providing solution to a portion ofa vessel, the method comprising: providing a microcatheter having anelongate tubular body with a lumen extending axially therethrough and anoutlet port, and a tip portion distal and eccentric to said elongatetubular body, said tip portion having a tip portion lumen extendingaxially therethrough; placing a guidewire in the vessel; advancing themicrocatheter into the vessel by placing the guidewire through the tipportion of the microcatheter and advancing the microcatheter over theguidewire; introducing solution into said elongate tubular body at saidbody proximal end; and injecting said solution into the vessel throughsaid outlet port while the guidewire is positioned within the tipportion.
 21. The method of claim 20, wherein said solution is atherapeutic or diagnostic solution.
 22. The method of claim 20, furthercomprising introducing and advancing a second guidewire into saidelongate tubular body at said body proximal end.
 23. The method of claim22, further comprising exchanging the second guidewire for a thirdguidewire by withdrawing said second guidewire from said elongatetubular body, and introducing and advancing a third guidewire into saidelongate tubular body at said body proximal end.